In the terrifying footage, believed to have been taken on a dashcam, he repeatedly hits the driver's window with the weapon and then heads round to the other side of the vehicle and smashes the front passenger window. The driver then fleas on foot, while other members of the public watch in horror.

Gardener, of London Road in Thornton Heath, was found guilty of attempting to cause grievous bodily harm (GBH) with intent in relation to the incident at the Old Bailey last Wednesday (November 21). He had previously pleaded guilty to affray and being in possession of an offensive weapon.

He was due to be sentenced at the Old Bailey on Monday (November 26), but the hearing was instead adjourned until Tuesday (November 27).

After the hearing, prosecution barrister Kate Fortescue told Croydon Advertiser it was most likely that Gardner and the victim knew eachother, although it is not known in what capacity.

This is mainly because the 19-year-old driver didn't give evidence at the trial or give a statement to police.

'You can see a stabbing motion towards the victim'

Gardner, looking rather relaxed in the dock in Court 3 at the Old Bailey, was dressed all in grey during the sentencing, and had distinctive black braided hair.

Ms Fortescue briefly told the court on Monday about the events of May 30.

She said: “In the video you can see the defendant get off his bike... and hit a knife repeatedly on the driver’s window.”

Joshua Gardner hit the front window six times with the knife as the driver sat inside

She added: “The defendant smashed the passenger window and you can see his arm go through the window and you can see a stabbing motion towards the victim.”

Ms Fortescue didn’t tell the court of any reason why Gardner would do this.

Mark Stevens, defending Gardner, told the court that the teenager’s oldest brother died when he was just 13-years-old.

To make matters worse, at around the same time as this happened, Gardner’s other brother, who was also older than him, moved away.

Mr Stevens told the court that Gardner “knows his actions are so wrong he needs to be punished”.

“There are really positive signs he can mature and can give something back to the community,” he added.

Joshua Gardner chased after the car and kicked one of the rear passenger doors

Judge Anuja Dhir QC, who became the first non-white circuit judge to sit at the Old Bailey last year, said a probation officer had told her on Monday morning that Gardner was a “quiet and young man”.

She adjourned the sentencing hearing until Tuesday, and told the court this was because she wants to consider all sentencing options. A probation officer was due to speak with Gardner and his mum after the short hearing, before giving feedback to Judge Dhir.